Fix markdown syntax for pandoc

[am11]

Running the SDK manpage tool (https://github.com/dotnet/sdk/tree/main/documentation/manpages/tool which we run once a year) was complaining about the changes made in 1de0076.

$ cd sdk/documentation/manpages/tool
$ ./run_docker.sh
...
Working on docs-main/docs/core/tools/dotnet-new-sdk-templates.md
Traceback (most recent call last):
  File "/manpages/tool/remove-metadata-and-embed-includes.py", line 67, in <module>
    sys.exit(main(sys.argv))
  File "/manpages/tool/remove-metadata-and-embed-includes.py", line 59, in main
    lines = read_lines_document_file(filename, original.readlines())
  File "/manpages/tool/remove-metadata-and-embed-includes.py", line 51, in read_lines_document_file
    assert False, 'Unable to parse: ' + line
AssertionError: Unable to parse: [!INCLUDE [](../../../includes/templates.md)]

cc @tdykstra
FYI: @jkoritzinsky @marcpopMSFT

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